Passing in special characters from a perl script to csh

Question

I'm writing a perl script that takes a string and passes it into a .csh script.

PerlScript.pl:

$CMDLineArgs = "-stuff -more_stuff \'-even_more \"*stuff\" -last_stuff\'";
system(Script.csh $CMDLineArgs);

Script.csh:

set flags="$argv[*]"

For some reason the single quotes aren't making it into my .csh script, and the entire thing won't work if * is anywhere in the string. Any suggestions on how I can get the string exactly as it appears in the perl script into the csh script?

Answer 1

Perl provides for a variety of quote-ing operators for just such a scenario as you seem to be having. In particular, the qw//, qq//, and q// operators, standing for quote word, double quote string, and single quote string operators respectively. You will notice that they completely take away the drudgery out quoting data.

And as has already been pointed out, the system() command is better served using arguments served via a list rather than in scalars for security reasons.

Finally, inside the cshell code, you need to use the :q modifier to quote the variable.

%  cat PerlScript.pl

---

my @Args = (
   qw/     -stuff  /,                    # whitespace ignored
   qw/ -more_stuff /,                    # whitespace ignored
   q['-even more "*stuff" -last_stuff'], # whitespace IMPORTANT
);

my $csh_script = q[Script.csh];

system($csh_script, @Args) and
   die qq[Error: The script $csh_script has failed with exit code:], $? >> 8;

---

% cat Script.csh

---

foreach arg ( $argv[*]:q )
   echo "<$arg>"
end

---

Results

<-stuff>
<-more_stuff>
<'-even more "*stuff" -last_stuff'>

---

Notes

• If you don't think the output is to your liking, then DONOT change anything inthe csh script. Rather play with @Args in the PerlScript.pl file.
• For example, if you were to populate the @Args like as shown:

---

my @Args = (
   qw/     -stuff  /,
   qw/ -more_stuff /,
   q['-even more],
   q["*stuff"],
   q[-last_stuff'],
   #q['-even more "*stuff" -last_stuff'],
);

Then you would see the following result:

<-stuff>
<-more_stuff>
<'-even more>
<"*stuff">
<-last_stuff'>

Answer 2

There may be other ways to do it (I'm no expert in csh/tcsh - i disliked csh when i had to use it in the early 90s and have avoided it as much as possible ever since) but the only way I've found to do what you want in tcsh is with set nonomatch or set noglob. For example:

perlscript.pl:

#!/usr/bin/perl

@CMDLineArgs = ('-stuff', '-more_stuff', '-even_more', '*stuff', '-last_stuff');
system('./script.tcsh', @CMDLineArgs);

alternatively, if you don't want to type all the single-quotes and commas, use qw():

@CMDLineArgs = qw(-stuff -more_stuff -even_more *stuff -last_stuff);

script.tcsh:

#!/bin/tcsh

set nonomatch
set flags=($argv[*])

foreach f ($flags)
  echo $f
end

and the output is:

$ ./perlscript.pl
-stuff
-more_stuff
-even_more
*stuff
-last_stuff

Note how this keeps each argument as a separate element in $flags, instead of concatenating them all into a single string.